The present invention relates to a power operated rotary knife with an improved blade housing and clamping assembly.
Power operated rotary knives have been used in commercial meat processing operations to trim fat and connective tissue from meat, trim pieces of met from bones, and to produce meat slices. Such knives are often constructed so that they are driven via a long flexible drive shaft. The knife operator wields the knife relatively freely at a meat cutting work station that is remote from the driving motor.
The blade of a power operated rotary knife must be replaced periodically. To permit easy removal of the blade from a blade housing, a split blade housing has been employed. Such a split blade housing is disclosed in published PCT Application No. PCT/US00/27488 (International Publication No. WO 01/24977 A2), assigned to the assignee of the present invention and which is incorporated herein in its entirety by reference.
A clamping assembly is used to secure the blade housing to a head member of the knife. The clamping assembly includes a clamp body and a pair of clamping screws. The pair of clamping screws extend through holes in the head member and into tapped holes in the clamp body. The clamping screws are tightened to secure the blade housing to the head member.
The blade housing includes a slot on its outer periphery to facilitate remove of the blade from the blade housing without the necessity of removing the blade housing or the clamp body from the head member. To remove the blade, the clamping screw nearest the blade housing slot is slightly loosened, a screwdriver is inserted in the slot and levered against the head member to resiliently expand the blade housing diameter and, thereby, release the blade from the blade housing. Upon installing a new blade, the screwdriver is removed from the slot and the blade housing returns to its unexpanded diameter and the clamping screw is tightened. Frictional forces between the blade housing, clamp body and head member maintain the blade housing in its unexpanded condition.
It has been found that some operators of such rotary knives fail to tighten the clamping screw sufficiently after installing a new blade. During cutting operations, forces are applied to the split housing that tend to spread it apart. If the clamping screw is not sufficiently tightened, the blade housing diameter may gradually expand during use of the knife. Expansion of the blade housing during use of the knife may result in chattering of the blade, poor cutting performance and downtime as the operator attempts to analyze and remedy the problem. To avoid this problem it would be desirable to provide an inexpensive and reliable structure to increase the frictional force between the blade housing and the clamp body that maintain the blade housing in its unexpanded condition during use of the knife but that still permits easy changing of the blade by loosening of a single clamping screw.
The present invention provides for an improved rotary knife comprising an annular blade, a split blade housing for supporting the blade for rotation, a handle assembly including a head member for supporting the split blade housing, and a clamping assembly including a clamp body for clamping the split blade housing to the head member.
An important feature of the invention is that a portion of the split blade housing is provided with an area of scoring along a bearing surface that bears against the clamp body. Similarly, the clamp body is provided with an area of scoring along a bearing surface that bears against the blade housing bearing surface. The areas of scoring coact to inhibit movement of one end of the split blade housing with respect to a second end of the split blade housing when the split blade housing is clamped to the head member. Preferably, the scoring of the clamp bearing surface of the blade housing comprises lines of scoring defining a pattern of alternating ridges and grooves and the scoring of the blade housing bearing surface of the clamp body comprises lines of scoring defining a pattern of alternating ridges and grooves. The lines of scoring of the blade housing are configured to inter fit with the lines of scoring of the clamp body, that is, the ridges of the clamp body engage the grooves of the blade housing and the ridges of the blade housing engage the grooves of the clamp body to increase the frictional force between the clamp body and the blade housing.
These and other objects, features and advantages of the invention will become better understood from the detailed description of the preferred embodiments of the invention which are described in conjunction with the accompanying drawings.